Combining waterborne bionutrients with scale particles and use of a waterborne particle remover to remove the combined particles from the water

ABSTRACT

An automatic, self-regulating method of water treatment for use in water circulating towers in which water is evaporated, and make up water is added, with components which synergistically function to cut chemical, energy, water, corrosion, pollution, and maintenance costs, by passing the water through a Water Conditioning unit to prevent adhering evaporation scale deposits along with their content of concentrated biofouling nutrients from forming on the flooded surfaces of the tower and its associated water flow circuit, adding a trace level of iodine to the input make-up water to enhance the further disinfection of nutrient-deprived surfaces from any residual biofilm and chance pathogen contaminations, and adding a trace level addition of zinc ions in the water such as by an assured treatment feeder to the input make-up flow for inhibiting residual iodine-resistant algal and bacterial organisms of hazard for restoring bionutrient tower conditions, such as within sun-lit environments, and apparatus for carrying out the foregoing method.

This is a continuation of prior U.S. application Ser. No. 10/876,449filed on Jun. 28, 2004, now U.S. Pat. No. 7,497,953 which claims benefitfrom the provisional application Ser. No. 60/487,244, filed on Jul. 16,2003, which is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

A water treatment method using a unique synergistic combination of watertreatment components performing treatment steps automatically andcontinuously applied to the make-up and recirculation waters inevaporative cooling towers, and to apparatus for the application of sucha method.

BACKGROUND OF THE INVENTION

Cooling towers are widely used in H.V.A.C. and Industry. The towers willnormally employ evaporation of water, and heat exchange the buildingHVAC circulating water, to cool water. The evaporation results in theconcentration of dissolved solids in the cooling tower recirculationwater. Scale, principally in the form of calcium carbonate, can buildup, thereby reducing the rates of heat transfer and hence the efficiencyof the tower. The water is also suitable for the growth of biologicalcontaminants such as bacteria and algae. Biofouling organisms, usingorganic nutrients collected by scale deposits, attack system surfaceswith corrosive acids to further increase dissolved particulatecontamination. Conventional chemical treatment, particularly sincechromates were banned by E.P.A., in practice, does not control scale,corrosion or microbiological contamination, and produces the potentialliability of toxic discharge water into the environment, and handlingbarrels of toxic chemicals.

U.S. Pat. No. 4,830,761, Leach et al. disclose a method of recirculationcooling tower basin water through a series of filter bags in order toreduce the amount of particulate contamination. In U.S. Pat. No.6,332,978, Cushier et al. teaches a combination of filtration andtreatment with redox media to reduce contamination in recirculationcooling tower waters. However, scale is not controlled, backwashingcycles are mandatory, and the copper compounds used plate out onto themetals of the equipment. Ozone treatment, among other disadvantages,does not prevent scale formation and is restricted in application. Theknown prior art methods do not eliminate scale, and do not offer 24hour/day, automatic, effective protection against legionella, scale,corrosion and microbiological contamination.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved method and apparatus forautomatically eliminating scale, minimizing particulate contaminants,legionella and controlling corrosion, fouling & microbiologicalcontamination in cooling tower recirculation water, 24 hours per day.

In particular, the invention provides a first Module A for the treatmentof incoming make-up water, and a second Module B for the treatment ofthe cooling tower recirculation water. The first Module A directs someincoming make-up water through an iodine canister (18), and also througha micromineral suppressant canister (20), containing zinc, in order toprovide metered, low levels of iodate and zinc, to suppress bio-organiccontamination throughout the tower. All incoming make up water alsopasses through a physical type, self-cleaning water conditioner (22),which prevents the formation of scale dissolves old scale and inhibitscorrosion.

The second Module B includes a pump (24) that recirculates the towersump water through a strainer (26), a centrifugal separator (28) and aphysical type, self-cleaning water conditioner (30) which maintains thewater in an unsaturated state. The strainer (26) removes the largerparticulates and any debris that gets into the tower (32). Thecentrifugal separator (28) brings the particulates down to minus 40microns throughout the recirculation system, in addition the conditioner(30) produces large calcium carbonate particles, which in turn coagulatewith the organics, and are blown down by the separator (28) and a“blow-down” valve.

An alternative second Module B can consist of a bypass pipe installedacross the cooling tower recirculation pump inlet and outlet pipes; withthe separator (28), conditioner (30) and flow meter (34) mounted in thisby pass pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. is a schematic representation of a typical cooling tower whichillustrates with Module “A” and Module “B” a preferred method andapparatus for automatically treating water according to the invention;

FIG. 2. is a schematic representation of the self-regulating zincgenerator (20), which in conjunction with FIG. 3 schematic is attachedto the make up water line (36);

FIG. 3. is a schematic representation of the self regulating iodinegenerator (18), which in conjunction with FIG. 2 is attached to the makeup water line. (36);

FIG. 4. is a diagrammatic drawing of a laser particle test result beforehard water entered the conditioner;

FIG. 5. is a diagrammatic drawing of a laser particle test result, inthe same water as in FIG. 4, after the water had passed through the sameconditioner.

DETAILED DESCRIPTION

Cooling towers are designed to work on an evaporative process inconjunction with a heat exchanger/chiller condenser (14). A tower (32)will typically include baffles or fill and spray bars (16) or likeelements having increased surface areas over which warm water cascades.At the same time, cooling tower fans (not shown) move air over thecascading water to increase evaporation and lower the water temperature.The resultant cooled water is cycled back through a chiller condenser(14) where it picks up heat and is then returned to the tower (32) to becooled. As the water evaporates in the tower (32), the dissolved solidsin the water which collect in the tower sump (10) become concentrated.To maintain a constant water volume within the system, make-up watermust be continuously added to compensate for the water lost throughevaporation in the tower (32), and through ‘blow-down’.

Scale builds up in the chiller condenser (14) and in the fill and spraybars (16) in the tower (32) with conventional chemical treatment. Thisscale reduces the heat transfer efficiency of the condenser (14). Inaddition, the cooling tower water is subjected to biologicalcontamination by airborne micro-organisms from the air, which are suckedinto the tower (32) by the fans. Microbiological contamination of thistype entering the cooling tower recirculation water is a major cause ofcorrosion of metallic surfaces due to bio-film formation. Known chemicalwater treatment processes result in having to ‘rod-out’ chillercondenser tubes (14) and/or “acid-wash”, to reduce excess energy costs,and protect the system from severe damage.

To prevent and control the problems of scale and fouling, high corrosionrates (usually >3 m.p.y. with conventional chemical treatment), and lowcooling tower life span the present invention automatically performsseveral functions, some by themselves and others in conjunction with oneanother, as follows:

FIG. 1 is a schematic representation of a cooling tower treatment systemillustrating the present invention. A typical cooling towerinstallation, portions of which are illustrated in FIG. 1, includes amake-up water line (36) discharging fresh water into the tower sump (10)continually replacing the total amount of water loss from evaporationand sump discharge water losses. A cooling tower recirculating pump(s)(12) circulates cooled water from the tower sump (10) through thecondenser side of a heat exchanger (14), where it picks up building heatfrom the evaporator side of the chiller (14), and then from there ispiped to a spray bar system (16) mounted at the top of the tower (32).The water from the spray bars (16) cascades down into the tower sump(10), and then is piped back into the condenser side of the heatexchanger (chiller) (14).

In this preferred embodiment a typical cooling tower is fitted with thegroups of components identified as Module A and Module B in FIG. 1,which go to make up the invention.

Module A, which treats incoming make-up water, consists of an iodinegenerator canister (18), (see FIG. 3) a mineral suppressant generatorcanister (20) (see FIG. 2) and a physical type water conditioner (22).

Module B schematically depicts a side stream sump recirculation line,consisting of a strainer (26), a pump (24), a separator (28) & aphysical-type water conditioner (30). Conditioner (22) used in Module A,and conditioner (30) used in Module B are physical type, self-cleaning,require no chemicals or electricity, and are maintenance free. Dependingon water quality, physical type water conditioners such as capacitanceor magnetic designs may be used that can produce large sized calciumcarbonate particles in hard water, as measured by independent laserparticle counts ‘before’ and ‘after’ hard water passes through theconditioner, as shown in FIG. 4 and in FIG. 5; also producing a minimumincrease of 300% turbidity and 200% suspended solids. A capacitance typeunit that may be used in either or both Module A and Module B isdisclosed in U.S. Pat. No. 5,695,644. A suitable magnetic unit isdisclosed in U.S. Pat. No. 4,422,933.

Conditioners other than those mentioned above can also be used if theyoffer the above required characteristics.

The conditioners (22) and (30), prevent the formation of scale, causethe dissolution of old scale and inhibit corrosion throughout thesystem. With the scale removed, and automatically maintained that way,the ferrous and ferric oxides then combine to form magnetite on thepiping surfaces. Without the presence of scale, nutrients formicro-organisms are reduced to a minimum. In addition to a scale freeenvironment, a very clean water system is maintained by a centrifugalseparator (28) that reduces particulate contaminants down to minus 40microns in the system (manual or automatic blow-down). Further reductionin the number of contaminant particles is achieved by the action of theconditioners (22) & (30) which automatically produce large sized calciumcarbonate particles throughout the recirculation water system on acontinual basis when treating hard water. These growing calciumcarbonate particles coagulate with the organics thereby preventingfurther corrosion as a result of the elimination of the organicnutrients, and are continually removed from the system by the sumprecirculation line separator (28) and by the ‘blow-down’ valve (38).This blow down valve (38) is a valve which can be installed inalternative places but usually into a pipe which eminates from the sump(10). It is actuated electrically by a timer, which in turn is signaledelectrically from the make up water line meter. This water meter is preset to signal the timer for (say) every 25 gallons flowing through themake up water pipe (36). The timer can be adjusted for controlling theconcentration of the chlorides in the cooling tower water. The strainer(26) installed before the sump recirculating pump (24) eliminates largerparticles and debris.

Water that has been cooled by evaporation in the tower (32) is collectedin the sump (10). The cold sump water is piped back into the chillercondenser (14) by the main recirculation pump(s) (12). The heated waterexiting the chiller condenser (14) is returned to the tower (32) forevaporative cooling. The water in the sump (10) is cycled through ModuleB by a pump (24). Larger particulate contaminants are removed from thewater by a strainer (26). Particle size of scale and other contaminantsthroughout the cooling tower system is reduced below minus 40 microns bythe Model B separator (28). Water directed back to the sump (10) passesthrough a water conditioner (30), which further ensures elimination ofcalcarious and organic contaminants, maintaining the recirculation waterin an unsaturated mode, with the continual production of large calciumcarbonate particles. Incoming make-up water is treated in Module A bythe iodine conditioner (18), zinc conditioner (20) and water conditioner(30).

The make up water assembly incorporates two ‘see through’ type similarcanisters containing zinc in one canister (20) and iodine in the othercanister (18)

In the zinc canister (20) at the bottom of the vertical canister thereis an inlet tube (40), with nozzle holes (42) designed to exit the waterinto the nozzle cone (44), creating a deep penetration scrubbing actionon the zinc. In the iodine canister (18) there is an inlet tube (46)with holes (48). This design does not have a nozzle cone since a lesseraction is desirable. This internal design difference is to obtain themaximum desired water action for each of the two elements, ensuringconsistent results, i.e., the scrubbing action on the zinc, which isless desirable on the iodine. The feed water for the two canisters (18)and (20) is derived from some of the make-up water being diverted fromthe make up water pipe (36) by an adjustable valve, located in the makeup water line, between an inlet pipe and an outlet pipe to thegenerators. This water passes through the iodine canister (18), tointroduce iodine; and some of this make up water diverted into themicro-mineral suppressant canister (20), for zinc to be metered inamounts sufficient to control bio-organic contaminants. The iodine isdischarged from the iodine canister (18) through a ‘see through’ typehorizontal flexible tube to a needle valve, that controls the iodinedischarged back into the make up water main pipe (36). Concentratediodine is very aggressive, so all materials used have to be neutral toiodine. The micro-mineral suppressant canister (20) internal parts anddesign to generate zinc, has to be constructed to a modified fluidizedbed principle for ensuring that the surfaces of the zinc are constantlyself-scrubbed when operating, for consistent erosion release, giving anon-going accuracy of correct metering, even for small injections, themetering being controlled by the aforementioned adjustable valve in themake up water line.

An additional benefit offered by the invention is that, as the waterconcentrates, build up of total dissolved solids, hardness (as CaCO3),TDS, conductivity levels are reduced by about 40%, as compared toconventional chemical treatment, thereby permitting increased cycles ofconcentration, and considerable water savings. This occurs because thecalcium carbonate particles produced by the conditioners combine withthe organics, which together then have a specific gravity heavy enoughto be automatically discharged. As an example, in Great Lakes Water,cooling tower water use and discharge is reduced by at least 25%. Inaddition to this water savings, in hard make up water situations, evenmore water is saved compared to chemical treatment which has to ‘soften’this water before use, involving the additional cost of an appropriatelysized water softener, plus having to use quantities of salt. In additionto this expense, the ‘softener’ has to be regenerated on a regular basis(such as twice/week), which uses up large quantities of water. Thesystem, according to the invention, does not require a softener in hardwater. Cooling towers using chemical treatment, use vast quantities ofwater, whereas according to the invention, up to 40% water use anddischarge can be saved.

The above description explains how the total recirculation water istreated, which creates and maintains a very clean system, a mandatorycondition for effective prevention of microbiological contamination. Theinvention adds to this bacterial control by automatically and accuratelymetering into the make up water line (36), as described below <250p.p.b. of zinc, and <200 p.p.b. of iodine for bacteria kill. The iodine,then has a final adjustment to reflect 1 p.p.m. in the recirculationwater. The iodine becomes iodate, due to the aeration of the sumpcascading water. The iodate in a clean system, at 1 p.p.m., killslegionella up to 99.99999% (U.S. Dept. of Health—Atlanta). The zinc,when present at only 50 p.p.b., kills pseudomonas & other pathogens.Pseudomonas when present is harmful because it regenerates bio-nutrientswhich are a major source of nutrients for legionella. The iodatepenetrates under bio-films, even penetrates amoebas thereby killinglegionella. Algae is efficiently controlled by the combination of iodateand zinc.

Each canister holds enough zinc and iodine to last 2 to 3 years before arefill is required. This replenishment is a simple operation, and takesapproximately 20 minutes. A test valve or tap (50) in provided in moduleA. By opening this valve (50) and collecting a sample of the water, itis possible to sample the iodine content of the make up water, and thusensure that the percentage is adjusted to produce optimum results.

Depending on water quality, other metals at <500 p.p.b. may possibly beused in addition to, or in place of zinc. The water quality throughoutthe system is always maintained to potable standards, when the make-upwater is of potable quality.

To summarize the operation, water that has been cooled by evaporation inthe tower (32) is collected in the sump (10). The cold sump water ispiped back into the chiller condenser (14) by the main recirculatingpump(s) (12). The heated water exiting the chiller condenser (14) isreturned to the tower (32) for evaporative cooling. The water in thesump (10) is cycled through Module B by a pump (24). Larger particulatecontaminants are removed from the water by a strainer (26). Particulatesize of scale and other contaminants throughout the cooling tower systemis reduced below minus 40 microns by the separator (28). Water directedback to the sump (10) passes through a water conditioner (14), whichfurther ensures elimination of calcarious and organic contaminants,maintaining the recirculation water in an unsaturated mode, with thecontinual production of large calcium carbonate particles. Incomingmake-up water is treated in Module A by the zinc, iodine and a waterconditioner (22).

The make up water assembly consists of two ‘see through’ type similarcanisters containing zinc in canister (20) and iodine in canister (18),the difference in the two canisters being basically that the waterdischarge holes at the bottom of the vertical canister inlet tube aredesigned to exit the water into a nozzle cone (44) for the zinc, butdirectly out into the canister, above the disc, for the iodine. Thisinternal design difference is to obtain the maximum desired water actionfor each of the two metals, ensuring consistent results. The feed waterfor the two canisters is derived from some of the make up water beingdiverted from the make up water pipe (36) through the iodine canister(18), to introduce iodine, which converts to iodate with the aeration inthe tower; and some of the make up water diverted into the micro-mineralsuppressant canister (20), for zinc to be metered in amounts sufficientto control bio-organic contaminants. The iodine is discharged from theiodine canister (18) through a ‘see through’ type flexible tube to aneedle valve, that controls the iodine discharged into the make up watermain pipe (36). Concentrated iodine is very aggressive, so all materialsused have to be neutral to iodine. The micro-mineral suppressantcanister (20) internal parts and design have to be constructed to amodified fluidized bed principle for ensuring that the surfaces of thezinc are constantly self-scrubbed when operating, for consistent erosionrelease, giving an on-going accuracy of correct reading, even for smallinjections. To attain the scrubbing of the zinc surfaces, FIG. 2 showsthe inlet water entering the conventional filter exit into the uppercanister centre, and being discharged out of the bottom of the internalvertical tube, through equally spaced and angled holes (42) discharginginto a cone (44). This creates a swirling action on the zinc granules,contained in the canister (20) resulting in the scrubbing of the zincsurfaces, which prevents the surfaces from oxidizing.

All the make-up water then passes through the Module A waterconditioner(s) (22), which changes the water into an unsaturated state,dissolves old scale, and inhibits corrosion.

The system shown in schematic FIG. 1 is for the purposes of illustrationonly, and is not intended to be limiting, since cooling towers aredesigned with many different types of configurations, including, but notrestricted to, direct & indirect evaporative cooling towers, ‘coolers’,mechanical draft, hyperbolic towers etc.

The invention can operate efficiently for any type or size of coolingtower. Persons could generate additional embodiments without departingfrom the spirit of the claimed inventions. For instance, all or part ofthe make up water assembly could be applied to controllingmicrobiological contamination in water systems, for example to controllegionella etc. The schematics provided are to facilitate understandingof the invention only. Also water quality for the make-up water variesover a wide range, and therefore has to be treated accordingly sometimesbefore entering the make up water line. (36).

This water treatment method greatly improves the operation of coolingtowers; namely, in the permanent elimination of scale build-up on alltower and heat exchanger surfaces; in the effective control ofbiofouling; in the related suppression of biofilm sponsored corrosionand in the eradication of tower contamination by biological growths,particularly of pathogenic organisms, such as legionella. This resultsin a very effective, 24 hour/day, 7 days/week automatic control ofscale, fouling, corrosion, and microbiological contamination. The systemensures minimal heat transfer losses and pollutional water discharges,with greatly reduced water and energy consumption, applied chemicalquantities and operational and ownership costs, and greatly extendedcooling tower life. The foregoing is a description of a preferredembodiment of the invention which is given here for the purposes ofillustration. The invention is not to be taken as restricted to any ofthe specific features as described but comprehends all such variationsas come within the scope of the following claims.

1. A method of controlling proliferation of biofouling organisms by atleast substantially removing organics that are consumed by thebiofouling organisms, comprising: providing a particle separator capableof removing particulates provided that the particulates are no smallerthan a particular size of about 40 microns; providing water from acooling tower that is to be processed and recirculated back to thecooling tower, which water contains both scale-forming materials and theorganics; cycling the water from the cooling tower through a physicaltype water conditioner to form solid particles comprising calciumcarbonate of at least the particular size from the scale-formingmaterials; returning the water containing the formed solid particles tothe cooling tower to facilitate coagulating at least a substantialportion of the organics with the solid particles to thereby providecorresponding combined scale and organic particles of at least theparticular size; passing the combined scale and organic particlesthrough the particle separator to thereby remove at least substantiallyall of the combined scale and organic particles that are of at least theparticular size from the water.
 2. The method of claim 1 wherein theparticle separator comprises, at least in part, a centrifugal separator.3. The method of claim 1 wherein the physical type water conditionercomprises, at least in part, a capacitance-type water conditioner. 4.The method of claim 1 wherein passing the combined scale and organicparticles through the particle separator to thereby remove at leastsubstantially all of the combined scale and organic particles that areof at least the particular size from the water comprises passing thecombined scale and organic particles through the particle separator tothereby remove at least substantially all of the combined scale andorganic particles that are of at least the particular size from thewater on a substantially continuous basis.